Let’s say we’re in contact with space aliens. How would we talk to them? Google Translate has no setting for “English into Extraterrestrial,” after all.It turns out the government has studied this question. Specifically, a legendary US government code breaker once wrote a monograph titled “Communication with Extraterrestrial Intelligence.”

Aliens have been in the news lately because British physicist Dr. Hawking said on his new TV show that E.T.s, if they ever arrive, might be looking for conquest and plunder.

Even if that’s true, it would be useful to be able to communicate your message (“Please don’t vaporize that skyscraper”). That’s the sort of thing National Security Agency cryptologist Lambros Callimahos was getting at when he wrote his unclassified paper on communications with aliens some 40 years ago.

Like Hawking, Mr. Callimahos assumed that any aliens who contact Earth probably will be our technological betters. Unlike Hawking, Callimahos thought this would be great. Imagine “the enormous potential gain from our contact with a superior civilization,” he wrote in the NSA Technical Journal in 1966.

Talking to E.T. could require the development of communication symbolism that is as easy as possible to comprehend, Callimahos wrote. He proposed a series of simple electronic beeps, first representing numbers, then increasing in complexity to indicate letters and mathematical processes.

Callimahos himself was complicated. Fascinated from childhood by both music and codes, he volunteered for cryptology during World War II, and eventually developed and taught the NSA’s most intensive senior cryptology course. He died in 1977 and was inducted into NSA’s Hall of Honor in 2003.